Clinically important drug-drug interactions in poly-treated elderly outpatients: A campaign to improve appropriateness in general practice

Aims The aim was to assess the impact of a campaign for general practitioners (GPS) to reduce clinically-important drug-drug interactions (DDIs) in poly-treated elderly patients. Methods We compiled a list of 53 DDIs and analyzed reimbursed prescriptions dispensed to poly-treated (≥four drugs) elderly (>65 years) patients in the Emilia Romagna region during January 2011-June 2011 (first pre-intervention period), January 2012-June 2012 (second pre-intervention period) and January 2013-June 2013 (post-intervention period). Educational initiatives to GPS were completed in July 2012-December 2012. Pre-test/post-test analysis (2013 vs. 2012) was performed, also using predicted 2013 data (P < 0.01 for statistical significance). Results Despite the slight increase in poly-therapy rate (16% in 2013, +1.5% from 2011), we found a stable or slightly declining number of potential DDIs for each elderly poly-treated patient (∼1.5). In 2013, 11 DDIs exceeded 5% of prevalence rate: antidiabetics-β-adrenoceptor blockers ranked first (20.3%), followed by ACE Inhibitors (ACEIs)/sartans-non steroidal anti-inflammatory drugs (NSAIDs) (16.4%), diuretics-NSAIDs (13.6%), selective serotonin re-uptake inhibitors (SSRIs)-NSAIDs/acetyl salicylic acid (ASA) (12.7%) and corticosteroids-NSAIDs/ASA (9.7%). A remarkable reduction emerged for NSAID-related DDIs (diuretics-NSAIDs peaked -14.5%; P < 0.01), whereas prevalence of antidiabetics-β-adrenoceptor blockers increased (+7.9%; P < 0.01). When using predicted values, the statistical significance disappeared for antidiabetics-β-adrenoceptor blockers (+1.3%; P = 0.04), whereas it persisted for almost all NSAIDs-related DDIs: ACEIs/sartans-NSAIDs (-3.0%), diuretics-NSAIDs (-6.0%), SSRIs-NSAIDs/ASA (-5.9%). Conclusions This campaign contained the burden of DDIs in poly-treated elderly patients by 1) reducing most prevalent DDIs, especially NSAIDs-related DDIs and 2) balancing the observed rise in poly-therapy rate with stable rate in overall prescriptions of potentially interacting drugs per patient.